Live Measles Vaccine Not a Cause of Atypical Measles Syndrome

Abstract

In the August issue of PIR (3:55, 1981)1 there is an abstract regarding atypical measles which we believe is misleading and may deter vaccination of a group of adolescents for whom live measles vaccine is indicated. We have received calls from a number of concerned pediatricians and believe the abstract should be corrected. The author states that the atypical measles syndrome is a possible consequence of administering live measles vaccine to former recipients of killed measles vaccine. Although severe local reactions and occasionally systemic reactions do occur following administration of live measles vaccine to former recipients of killed measles vaccine, there is no evidence that the live vaccine causes classic atypical measles syndrome.Three patients, referred to as having severe systemic reactions by Krause et al,2 experienced fever to 103 F (39.4 C), malaise, marked local pain, swelling and erythema seven days following vaccination; these reactions lasted an average of eight days. However, the abstract was incorrect because these patients did not develop the atypical measles syndrome. Although the reactions were more severe than reactions that might be observed in persons who had never received killed measles vaccine, they were substantially less severe than the atypical measles syndrome. Atypical measles is characterized by high fever, pneumonitis (often with pulmonary consolidation and pleural effusion), pedal and hand edema, and an unusual rash which may be maculopapular, petechial, vesicular or urticarial. The rash is often most concentrated on the extremities.3 Revaccination with live measles vaccine is indicated for former recipients of killed measles vaccine to induce permanent immunity to measles, so that the atypical measles syndrome does not develop when the vaccinee is exposed to natural measles. Revaccination will not cause the syndrome. Atypical measles has occasionally been reported in individuals exposed to natural measles who had previously received live measles virus vaccine within a few months of receiving inactivated measles vaccine.4-6 This raises the possibility that the temporary immunity conferred by the killed vaccine precluded an adequate immunologic response to the live measles virus vaccine. Therefore, persons who received live measles vaccine within three months of receiving inactivated measles vaccine should also be revaccinated with live measles vaccine. Killed measles vaccine was used in the United States between 1963 and 1967 when an estimated 1,836,000 doses were distributed. Persons vaccinated with an unknown type of measles vaccine during that period should also be revaccinated with live measles vaccine as the unknown vaccine may have been killed measles vaccine.